Sporothrix schenckii is a pathogenic dimorphic fungus which grows either in the yeast or in the mycelium form. At the present, very little information is available concerning the molecular mechanisms that control the expression of dimorphism in this fungus. Dimorphism in S. schenckii is an ideal model for the study of morphogenesis and cell proliferation because it allows the study of a proliferative process, a proliferative and morphogenetic process and the induction of a dormant cell into alternate pathways for differentiation in a minimal medium, at the same temperature of incubation by primarily manipulating the pH and the initial cell concentration. In addition, these transitions in S. schenckii react to effector molecules that have been identified to be involved in the control of cell proliferation and differentiation in other systems. Our objectives are: 1. to continue to study the involvement of Ca ions, PKC, inositol phosphates, cAMP and related substances on the development of the alternate forms of the fungus from yeasts or conidia; 2. to study protein synthesis during the formation of the alternate forms of the fungus which will include identifying phase specific polypeptides and the determination Ca binding or phosphorylation properties of polypeptides being synthesized during the development of the alternate forms of the fungus, in the presence and absence of effector molecules; 3. to isolate mRNA during the dimorphic transitions in the presence and absence of effector molecules and by in vitro translation identify polypeptides representing differences in the general pattern of protein synthesis, and 4. to determine the presence of genes functionally related to cAMP or Ca ions in this fungus and their expression during these transitions by identifying the presence of specific mRNA's. Our long term goals are to study the mechanism that control dimorphism in this fungus and to contribute to the general knowledge of how organisms control morphogenesis and proliferation using a lower eukaryote as a model system. This work will also provide broad training for graduate and undergraduate students in the basic techniques used in biomedical research.